XMPP as a Discord alternative for small group?

Hi. I have a group of 6 people using Discord to chat. Recently Discord changed a lot and we're looking for an alternative. We have a few requirements:

• Good client on multiple platforms
• Easy to use search
• Self hosted
• Permanently saved chat history & attachments on server (no expiration)
• Easy image upload (Ctrl+V to post image from clipboard)

IRC isn't an option as chat history is saved on the client, and there's no good integrated way to share files and preview images. Matrix would be an overkill as we're a small group not interested in federation, and the available clients had a few bugs. Mattermost lacks a good mobile app (their current one had bunch of bugs). XMPP appears to be the best as it is extensible and has many clients available.

However, I tried configuring prosody on my FreeBSD server and it seems like it doesn't permanently save chat history or attachment files. Does anyone know if these can be solved? Or is there any better alternative than XMPP?

Thanks.